1. Field of Invention
The present invention relates to conducting terminals attached to the container of an electrolytic device, and in particular to a battery terminal seal.
2. Description of the Related Art
It is well-known in the art of manufacturing electrochemical cells that one of the critical issues is the construction and maintenance of a hermetic seal between the conducting terminals and the cover of the container. A related problem is to electrically insulate terminals of opposite polarity, in order to prevent short-circuits which would impede proper functioning of the electrolytic process in the cell. In the case of a container having a metallic supporting surface, at least one of the polarity terminals must be hermetically sealed and electrically insulated from the container, and the container itself may be used as the second polarity terminal.
U.S. Pat. No. 5,663,015 to Hooke et al. and assigned to "Hawker Energy Products, Inc.", discloses a method of making a battery terminal seal. A moulded plastic nut having an internal thread to mate the external thread of the battery terminal fastens the terminal trough an orifice in the lid of the battery. The gap between the top surface of the terminal and the orifice provided in the lid is filled with a curable gasketing material. While the gasketing material is still uncured, the nut is rotated to compress the gasketing material so as to fill any gap between the terminal and the lid. However, the solution disclosed in the Hooke et al. patent is rather labourious because the radial and axial spread of the gasketing material while in an uncured state has to be restricted to the combination of the terminal, the fastener, and the top surface of the terminal. In addition, two sealing parts, i.e. the gasket and an O-ring, need to be compressed against the inner lid to prevent the spread of the electrolyte. The uncured gasketing material provides no compression force. After the material is cured, leakage prevention depends on the bonding properties of the material.
Canadian Patent No. 1,067,958 to Ching et al. assigned to "The Gates Rubber Company", discloses a sealed through-the-partition connector comprising a terminal with an enlarged and tapered bottom portion for mating with a deformable lead shroud, and for cooperating with an inverted frustroconical ramp portion defined in the connector seat. The seat should have some degree of resiliency to bias the deformable lead shroud in a mutually pressure exerting relation. If the connector seat lacks sufficient resiliency, it may creep under constant loading and to break the seal. While Ching et al. is concerned with sealing a battery terminal, it is not concerned with electrical isolation between the container and the conductive terminals.
Canadian Patent No. 298,379 to Swenson, discloses a lead nut with a tapered wall which is threaded upon a battery terminal to cause compression around the terminal. A central opening is defined in the cavity of a boss formed in the top wall of the container for receiving the external portion of the battery terminal. Two sealing parts, a rubber gasket and a rubber washer, are used for sealing the central opening when the nut is threaded downwardly on the terminal. This construction does not allow to use a metallic container, because the conductive terminals are not electrically isolated.
Accordingly, there is a need for a simple conductive terminal which can be used with both conductive and nonconductive supporting containers, while providing a good sealing for preventing electrolyte leakage.